Method of applying plastic insulation



Jan. 24, 1939. b. v. M GREW METHOD OF APPLYING PLASTIC INSULATION Filed Dec. 10,- 1936 2 Sheets-Sheet 1 Qfiivenfor/ GTWL'ZZQV Grew 4 o. v. M GREW METHOD OF APPLYING PLASTIC INSULATION Filed Dec. 10, 1936 2 Sheets-Sheet 2 Jan. 24, 1939.

Patented Jan. 24, 1939 METHOD OF APPLYING INSULATION rms'rlo Orville V. McGrew, Chicago, Ill., assignor to Dednox Corporation, a corporation of Illinois 3 Claims.

This invention is a plastic insulating and sound deadening composition and method and apparatus for its application. It is fully described in the accompanying specification and the apparatus is illustrated in the accompanying drawings in which,

Fig. 1 is a side elevation; Fig. 2 is a view of part of the apparatus looking from the left of Fig. 1; Fig. 3 is a horizontal section through the control apparatus; Fig. 4 is a section through the spray nozzle; and Fig. 5 is a diagrammatic view of the pump.

The plastic composition is composed very largely of granulated cork bonded with cutback asphalt mixed with a fine filler. The exact composition of a preferred compound will first be set forth, after which the general functions and necessities will be described. Inpractice I first make up what I term a glue base consisting of 45% Mid-Continent asphalt, 14% Gilsonite, melting point 275-280 F. and 41% V. M. & P. (varnish makers and painters naphtha).

The Mid-Continent asphalt is made from what is called Mid-Continent flux oil having an A, P. I. gravity at F. of 8.5, fiash 630 F., Engler viscosity at 210, 130, Engler viscosity at 300, 11.0, Engler viscosity at 350 F., 4.9. The fiux oil has a melting point of 93 F. and an asphalt content The foregoing figures are for identification only and can naturally be varied considerably.

This selected flux oil is blown to a maximum temperature of 550 F. for approximately two hours. The Gilsonite is then added and blowing continued at approximately the same temperature until a melting point of 200 and a penetration of 14 are obtained. The asphalt is then cooled to 300 and the naphtha is added. The naphtha will be varied to produce a viscosity of approximately 60 for winter temperatures and for summer temperatures.

In making up the insulating composition I mix 230 gallons of the above described glue base, 100 gallons V. M. 8: P. naphtha, 204 lbs. of 10-20 mesh cork, 50 lbs. of pulverized cork, lbs. 7K asbestos fibre, 200 lbs. 7M asbestos fibre, and 85 allons of water containing 1 lbs. chromic acid in solution.

The mixture thus formed is a plastic mass which can be appliedby spraying in the apparatus illustrated. It adheres with sufiicient tenacity either to vertical walls or to downwardly facing horizontal surfaces like ceilings to be self-sustaining, without slippage, or falling off when ap- Application December 10, 1936, Serial No. 115,254

the type shown diagrammatically in Fig. 5'. A 10 pump which is found to be satisfactory is one now marketed and known as the Viking rotary pump. The particular pump used has a rated capacity 01 20 gallons per minute at 1200 R. P. M.

In use the pump is operatedat 60 R. P. M. which delivers 1 gallon of the composition per minute. The pump may be driven in any convenient manner, but since compressed air must be available in any event for spraying, it is preferred to operate it by an air motor la. The pump l3 delivers the composition through a pipe I 5 from which it finds its waythrough a fitting It to a hose ll. At the end of the hose I1 is a spray nozzle l8 controlled by a valve Hi. In this nozzle the composition is carried through a central pipe 20 and compressed air is released around the emergent stream of the composition through an annular opening 2|, the air being supplied by'the compressed air line 22 controlled by a valve 23.

In order to prevent excess pressure in the hose .30

the control mechanism shown in Fig. 3 is employed. The fitting i6 communicates with a cylinder 24 in which is a spring pressed piston 25. Upon the occurrence of excess pressure in the cylinder 24 the piston moves out, pushing the rod 35 26 against a spring 21, closing a valve 28 in line 29 supplying air to the air motor.

The pump preferred is shown in Fig. 5. The charge enters at H and is discharged from l5.

Inside of the pump is a rotor 30 which is provided 40 with a number of teeth 3| separated by openings 32. An idler 33 is rotatably mounted within the pump and is provided with teeth 34 which fit snugly the openings 32. A baflle 35 is provided in the pump with a segment 36 cut therefrom to accommodate the idler teeth. In operation, the rotor turns in a counter-clockwise direction with the result that the idler teeth are withdrawn from the openings 32 as these openings pass the 50 inlet I]. This creates a suction which draws in a limited amountof material to the openings thus created. This material is then squeezed out near the discharge I5 by the re-engagement of the teeth 3| of the rotor with the slots in the idler ll sented themselves.

and the re-engagement of the idler teeth with the openings in the rotor,

In this operation the material is withdrawn in successive small increments by suction and is then forced under heavy pressure into holes.

The apparatus described has been found entirely satisfactory for the application-of the com} position which it sprays at the above, mentioned rate of a gallon a minute, with sumcient force to adhere easily to the surfaces against which the spray isdirected. It is found in practice that the massafter application is quite well filled with voids which provide insulating dead air spaces. These voids apparently arise in part'from air entrapped in the spraying operation and in part from the spaces left on the evaporation of the naphtha. The composition before application is quite free from voids.

The'development of the present apparatus and process has disclosed some interesting qualities of the compositionwhich considerably restrict the methods in which the composition can be handled. The bulk of the composition is obviously the granulated cork. The remainder of the composition, on superficial examination at least, seems only approximately to fill the voids the mass in the tank which would break the suction.

By the use of the present composition method and apparatus it is possible to apply quite thick layers of composition at very high speed. The composition adheres readily in any thickness likely to be used and when dried out by the evaporation of the bulk of the naphtha is quite rigid. The asphalt, however, is of the type which while having a very low temperature susceptibility is somewhat yielding or rubbery at all temperatures. The compound after application, therefore, possesses all the flexibility required to prevent it from chipping and breaking even when a metal surface to which it is applied is very seriously distorted.

The body provided by the application is not only an excellent heat insulator but is quite an effective sound deadener, and when applied to metal walls as in the case of the interior of automobile bodies, it is thoroughly effective in preventing the vibrations which, in many cases, are so objectionable. The application thus provided is peculiarly desirable in the case of automobile bodies because the coating can be used in thicknesses much greater than is feasible with the and to supply a rather thin coating on the cork"\inore common asphaltic compositions so the body granules. The cork granules themselves are,-of course, very readily compressible. After the development of the composition efforts were made to-apply it with a conventional spray apparatus in which the composition was to be forced to the spray nozzle by pressure applied on the tank. Two unexpected diillculties immediately pre- First, the mass tended to compress and squeeze out the somewhat fluid asphalt as water is squeezed out of a sponge, so that such material as did reach the nozzle was very irregular. Second, the compression of the mass by the driving pressure over it produced the very stiff rigid cork body which it was very difilcult to drive through a pipe which in many cases would not move at all. Thesedifliculties were overcome by employing the pump illustrated which sucks in the composition in small masses and exerts pressure under conditions where serious separation does not occur and where any compression of cork does not interfere appreciably with its transmission to the nozzle. Furthermore, if there be any change within the hose the composition is in a narrow stream where separation of the ingredients cannot produce large scale effects such as occur in a tank. Thus when the composition arrives at the nozzle and pressure is released it is practically in the same condition as when it left the tank.

It is, however, evident that if suction is to be relied upon to draw the composition to the pump, the composition itself must be sufliciently free from voids that no channels shall be left through hum or vibration can be reduced with exceptional efliciency. In the actual use of the composition it is generally applied in layers about half inch thick, and with material supplied at the rate of a gallon per minute the coating can be applied in this thickness at the rate of .about three cubic feet a minute.

What I claim as new and desire to secure by Letters Patent, is:

1. The hereindescribed method of applying a light semi-fluid tacky composition of cork granules and a semi-fluid binder, which consists in successively withdrawing small increments of such composition from a mass thereof packed in a container, by suction applied to the base of the container, forcing the removed material in a thin stream under pressure to the point of application and then spraying the composition with the aid of compressed air.

2. The method as set forth in claim 1, in which the composition consists of granular cork and cut-back asphaltic binder.

3. The hereindescribed method of applying a light tacky semi-fluid composition consisting of cork granules and a cut-back asphaltic binder,

which consists in withdrawing the composition ORVILLE v. McGREW. 

